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M57 The Ring Nebula

The Ring Nebula is a remarkable planetary nebula in the constellation Lyra, and a great favorite with amateur astronomers as it is bright and easy to observe even with fairly small telescopes.  This was my first deep space object that I personally found and observed on my own.  I was elated to actually find something in the mercury vapor lit washed skys of the Bay area.


This object was discovered by Antoin Darguier in 1779.  In his description he said that it was "as large as Jupiter and resembling a fading planet".  This was the first time that such a nebula had been compared with a planet, although it was Sir William Herscehel who made popular the description "planetary nebula".


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This nebula is more than 2000 light years from us according to modern determinations.  The ellipse is centered on a star which is one of the hottest to lie within a planetary nebula. Another star of similar magnitude lies within the boundaries of the nebula (upper left of the central star in this photograph), but this is a chance projection into the line of sight.

Since the ring's outer limbs (or edges) are quite clearly defined, astronomers have been able to observe the growth of this nebula over the past 50 years or so with modern telescopes. It appears to be expanding at 19 km/second (or 60 millionths the speed of light). Since its radius is on-third of a light year, the time which the nebula would take to get to its present size is about 5500 years. This figure gives the true age of the nebula if it has expanded at a more or less uniform rate. It is highly unlikely that such objects expand at a uniform rate but this is the best estimate that we can offer.